1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to an image display device which uses this liquid crystal display device.
2. Description of the Related Art
Liquid crystal display devices have been popularly used because of their characteristics that they are thin in configuration and exhibit the low power consumption. Particularly, a liquid crystal display device having active elements has a function of selectively giving potentials to respective pixel electrodes and holding such potentials and hence, the liquid crystal display device exhibits superior images compared with a liquid crystal display device of a type which has no active elements. Accordingly, the liquid crystal display devices of an active element type have been popularly used.
Further, as an image display device, an image display device which uses a so-called cathode ray tube has been known. Similarly, an image display device which uses a liquid crystal display device has been also known. The latter image display device exhibits less flickering compared with the image display device which uses the cathode ray tube and hence, images provided by the liquid crystal display device are gentle to human eyes. As the image display device using such a liquid crystal display device, versatile image display devices including liquid crystal monitors, notebook type personal computers, liquid crystal television sets, liquid crystal integral type personal computers PDAs and the like have been commercialized.
However, as a result of studies that inventors of the present application have extensively carried out, the inventors have found a new task that, with respect to the liquid crystal display device having active elements, when the operation is stopped, that is, when the supplying of power from the outside is stopped and thereafter the liquid crystal display device is again shifted to the operational state, there exists a case that a so-called flickering, that is, the strong unsteady shining of the screen appears.
The inventors also have found that this phenomenon is noticeable when the time counted from the stop of supplying of power to the supplying of power again is relatively short.
The inventors also have found that the above-mentioned phenomenon is further noticeable when the liquid crystal display device adopts a constitution in which an insulation layer is interposed between pixel electrodes and an orientation film or a constitution in which pixel electrodes and reference electrodes are provided on the same substrate and an insulation layer is interposed between layers forming these pixel electrodes and the reference electrodes.
A typical example of advantages brought about by the use of the liquid crystal display device in place of the cathode ray tube in the image display device is that the image display device exhibits the least flickering in addition to the previously-mentioned thin configuration and the low power consumption. However, the inventors have found that when the time for interruption of the supplying of power to the liquid crystal display device and the time for supplying power to the liquid crystal display device again in the image display device are short, even in the image display device using the liquid crystal display device, there exists a case in which the flickering is generated for several seconds to several 10s seconds immediately after power is supplied again. This gives rise to a crucial task that the liquid crystal display device may loose one of advantages thereof and hence, the inventors have made efforts to solve the phenomenon of this task and to cope with the task.
As a result of our efforts, we have found that following phenomena which will be explained in detail are main causes of the task.
In the liquid crystal display device having active elements, when selection potentials for making the active elements have the ON state are applied to scanning signal lines, the potentials are selectively written in the pixel electrodes and, for the most of the time, non-selection potentials for making active elements have the OFF state are applied to the scanning signal lines so that the voltage applied in the ON state is held. The reason that the active elements are in the OFF state in most of the time is that since the liquid crystal display device usually sequentially and selectively drive a plurality of scanning signal lines, in the liquid crystal display device which corresponds to XGA having at least 768 scanning signal lines, for example, it is a general driving method that the time in which the OFF state is selected is (768xe2x88x921) times longer than the time in which the ON state is selected.
Further, to prevent the deterioration of the liquid crystal material, the liquid crystal display device usually converts the potential applied between the pixel electrodes and the reference electrodes into an alternating current so as to prevent the direct current voltage from being continuously applied for a long time. However, this advantageous effect is merely obtained by inverting the polarity of the potential applied between the pixel electrodes and the reference electrode per one or a plurality of unit frames and hence, the effect only aims at the prevention of the applying of direct current voltage as the average for a long time. Accordingly, the fact that the substantially fixed voltage is applied to the pixel electrodes is not changed when viewed per each unit frame.
Further, the drive to invert the polarity of the potential applied between the pixel electrodes and the reference electrode per one or a plurality of unit frames can be performed only when power is supplied to the liquid crystal display device. That is, after such supplying of power is stopped, the applying of the approximately fixed potential to the pixel electrodes is continued. Then, at a point of time that the pixel electrodes are held at the OFF state due to the active elements, the pixel electrodes of the liquid crystal display device to which the supplying of power is interrupted are held at the OFF state for a relatively long time so that the applying of the fixed potential to the pixel electrodes is continued for a long time.
On the other hand, the potential is usually directly supplied to the reference electrode without through the active elements which are provided to respective pixels and hence, contrary to the pixel electrodes, after the supplying of power to the liquid crystal display device is stopped, the reference electrode immediately reaches the GND potential.
As a result, in the liquid crystal display device having active elements, when the supplying of power to the liquid crystal display device is stopped, the direct current potential difference is applied between the pixel electrodes and the reference electrode for a long time and the pixels are charged to the direct current. Accordingly, it has been found that even when power is supplied to the liquid crystal display device again, the potential between the pixel electrodes and the reference electrode at this point of time is driven in a mode that alternating current signals are superposed on the remaining direct current potential so that the imbalance is generated with respect to the liquid crystal drive voltage between polarities thus generating the flickering.
Further, it is found that the following is the reason that the generation of flickering is noticeable when the time counted from the stop of supplying of power to the restarting of supplying of power is relatively short. That is, when the supplying of power to the liquid crystal display device is stopped and a long time elapses thereafter, the potential of the scanning signal lines is converged to the GND state so that the leaking of charge stored in the pixel electrodes is generated through the active elements although a leaking amount is minute. Accordingly, when power is supplied to the liquid crystal display device again after the charge stored in the pixel electrodes is completely leaked, since the holding of the above-mentioned direct current potential between the pixel electrodes and the reference electrode is dissolved, no flickering is generated. Accordingly, when the time counted from the stop of supplying of power to the restarting of supplying of power is relatively short, the flickering is recognized noticeable in appearance.
It is also found that when the orientation film is arranged over the pixel electrodes, the orientation film performs the function of trapping the charge so that the above-mentioned flickering phenomenon is worsened.
It is further found that when an insulation layer is interposed between the pixel electrodes and the orientation film or when the pixel electrodes and the reference electrode are formed on the same substrate and an insulation layer is interposed between the pixel-electrode forming layers and the reference electrode-forming layers, these layers perform the function of trapping the charge and hence, the flickering phenomenon is further worsened.
Particularly, with respect to the liquid crystal display device in which the insulation layer is interposed between the pixel electrodes and the orientation film or the pixel electrodes and the reference electrode are formed on the same substrate and the insulation layer is interposed between the pixel-electrode forming layers and the reference electrode-forming layers, such a liquid crystal display device has been known as a device which can realize the wide viewing angle and hence, the further development of the device is expected as a device used for a liquid crystal monitor or a liquid crystal television set while substituting for a cathode ray tube. The fact that the flickering characteristics is further worsened in the liquid crystal display device having such a constitution constitutes an extremely crucial problem.
The present invention has been made in view of such circumstances and it is an object of the present invention to provide a liquid crystal display device which can suppress the generation of flickering when power is supplied again to the liquid crystal display device after the interruption of the supplying of power to the liquid crystal display device, and more particularly to an image display device which can suppress the generation of flickering by using such a liquid crystal display device.
The above-mentioned task to be solved is newly found by the same applicant of the present application and this task is described in detail along with means which can overcome the task in Japanese Patent Application 2000-372923 which is a prior application filed by the same applicant.
However, with respect to gate driver ICs or a gate driver circuit, some of them have a constitution which can elevate the gate OFF level but up to only the reference logic potential. Since the reference logic potential is usually at the GND level, that is, it is impossible to elevate the gate OFF level more than the GND level so that the liquid crystal display device which uses the gate driver ICs or the gate drive circuit having such a constitution has to face a new task that the flickering suppression effect is reduced.
Accordingly, it is another object of the present invention to provide a liquid crystal display device having gate drivers ICs or a gate drive circuit of a constitution which can elevate the gate OFF level only up to the reference logic potential or cannot elevate the gate OFF level to the reference logic potential, wherein the liquid crystal display device can suppress the generation of flickering when the supplying of power to the liquid crystal display device is restarted after the interruption of the supplying of power to the liquid crystal display device and to provide an image display device which can suppress the generation of flickering using such a liquid crystal display device.
To explain some typical inventions among inventions disclosed in the present application, they are as follows.
Means 1.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the improvement is characterized in that the potential of the scanning signal lines after the supplying of power to the liquid crystal display device from the outside is stopped is set to not less than GND level.
Means 2.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the improvement is characterized in that the potential of the scanning signal lines, after the supplying of power to the liquid crystal display device from the outside is stopped, has a mountain-like characteristic that the potential is once elevated after the supplying of power and thereafter is stopped and is converged to the GND level.
Means 3.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the improvement is characterized in that the liquid crystal display device includes a circuit which changes over the potential of the scanning signal lines after stopping the supplying of power to the liquid crystal display device from the outside to a potential which differs from the potential of the scanning signal lines in the normal drive state in which power is supplied to the liquid crystal display device.
Means 4.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the potential of the scanning signal lines is applied by a scanning signal line drive circuit and the scanning signal line drive circuit includes an input terminal to which power for non-selection potential of the scanning signal lines is supplied, the improvement is characterized in that the liquid crystal display device includes a circuit which changes over an input voltage to the input terminal to which power for non-selection potential is supplied after stopping the supplying of power to the liquid crystal display device from the outside with the input voltage to an input voltage which differs from the input terminal in the normal drive state.
Means 5.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the potential of the scanning signal lines is applied by a scanning signal line drive circuit and the scanning signal line drive circuit includes an input terminal to which power for non-selection potential of the scanning signal lines is supplied, the improvement is characterized in that the liquid crystal display device includes a circuit which changes an input voltage to the input terminal to which power for non-selection potential of the scanning signal lines is supplied after the supplying of power to the liquid crystal display device from the outside is stopped to a value which is different from the input voltage to the input terminal in the normal drive state and the circuit includes a Zener diode.
Means 6.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the potential of the scanning signal lines is applied by a scanning signal line drive circuit and the scanning signal line drive circuit includes an input terminal to which power for non-selection potential of the scanning signal lines is supplied, the improvement is characterized in that the potential of the input terminal to which power for non-selection potential of the scanning signal lines is supplied assumes a state in which the potential of the input terminal is set to not less than GND level after stopping of the supplying of power to the liquid crystal display device from the outside.
Means 7.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the potential of the scanning signal lines is applied by a scanning signal line drive circuit and the scanning signal line drive circuit includes an input terminal to which power for non-selection potential of the scanning signal lines is supplied, the improvement is characterized in that the potential of the input terminal to which power for non-selection potential of the scanning signal lines is supplied has a mountain-like characteristic that the potential is once elevated after stopping the supplying of power to the liquid crystal display device from the outside and thereafter is converged.
Means 8.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the improvement is characterized in that the charge of the pixel electrodes is rapidly released at a point of time that the supplying of power to the liquid crystal display device from the outside is stopped.
Means 9.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the improvement is characterized in that the holding of charge in the pixel electrodes is suppressed at a point of time that the supplying of power to the liquid crystal display device from the outside is stopped so as to prevent the generation of flickering at a point of time that power is again supplied to the liquid crystal display device.
Means 10.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the liquid crystal display device performs a display by generating the potential difference between the pixel electrodes and the reference electrode, the improvement is characterized in that the potential of the pixel electrodes is reset at a point of time that the supplying of power to the liquid crystal display device from the outside is stopped.
Means 11.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the potential of the scanning signal lines is applied by a scanning signal line drive circuit and the scanning signal line drive circuit includes a non-selection potential input terminal for the scanning signal lines and a reference logic potential input terminal, the improvement is characterized in that the potentials of the non-selection potential input terminal and the reference logic potential input terminal of the liquid crystal display device have a mountain-like characteristic that the potentials are once elevated after stopping the supplying of power to the liquid crystal display device from the outside and thereafter are lowered and the potential of the reference logic potential input terminal is set to a value not less than the potential of the non-selection potential input terminal.
With respect to scanning signal line drive circuits of the liquid crystal display devices, for example, gate driver ICs which are constituted of semiconductor chips or gate drive circuits which are constituted of semiconductors having crystallinity such as polysilicon, crystalline silicon or the like mounted on the substrates, some of them may be constituted such that a gate OFF level can be elevated only to the reference logic potential level. Usually, the reference logic potential level is set to GND level. Accordingly, in the liquid crystal display device having such a constitution, the gate OFF level can be elevated only to the GND level, that is, to 0 V.
Accordingly, in the liquid crystal display device using the scanning signal line drive circuit having the constitution which holds the gate OFF level state after stopping the supplying of power to the liquid crystal display device, it is impossible to sufficiently release the charge stored in the pixel electrodes after stopping the supplying of power from the outside. This is because that the it is impossible to bring the active elements into the complete ON state. In view of the above, the inventors have found a task that the effect to suppress the flickering at the time of interrupting the supplying of power or at the time of restarting the supplying of power becomes insufficient.
In view of the above, in the present invention, the reference logic potential of the scanning signal line drive circuit is separated from the GND level and the reference logic potential is configured to be controllable so that the above-mentioned task can be solved. By controlling the reference logic potential of the scanning signal line drive circuit in the above-mentioned manner, it becomes possible to elevate the gate OFF potential up to the ON potential of the TFT while holding the gate OFF potential to a value equal to or below the reference logic potential level so that the charge stored in the pixel electrodes of the liquid crystal display device can be released.
Here, it is needless to say that the advantageous effect of the present invention can be obtained even when the reference logic potential level of the scanning signal line drive circuit is always set to a constant value substantially equal to the ON potential of the TFT. However, from a viewpoint of the reduction of the power consumption, it is desirable that the reference logic potential level takes the usual GND level, that is, 0 V when power is supplied from the outside, reaches the state not less than the ON potential of the TFT after stopping of the supplying of power, and is converged to 0 V again thereafter so that both of the reduction of the power consumption and the flicker reduction effect can be achieved.
Means 12.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the potential of the scanning signal lines is applied by a scanning signal line drive circuit, the improvement is characterized in that the potential of the reference electrode becomes a negative potential after stopping the supplying of power to the liquid crystal display device from the outside.
To suppress the flickering which is generated at the time of cutting the supplying of power or at the time of supplying power again, it is sufficient to release the charge stored in the pixel electrodes at the time of cutting the supplying of power. To achieve such an aim, it is necessary to set the active elements to the ON state after stopping the supplying of power. In addition to a method which sets the potential of the scanning signal lines to the ON state, it becomes possible to set the active elements to the ON state by lowering the potential of the pixel electrodes to a value not more than a given value for the potential of the scanning signal lines. Usually, the potential of the pixel electrodes is the potential which is written when the active elements are in the ON state and cannot be directly changed when the active elements are in the OFF state.
However, since the capacitance is generated between the pixel electrodes and the reference electrode, by changing the potential of the reference electrode, the potential of the pixel electrodes can be changed due to the capacitive coupling. In this case, the reference electrode is mounted on a substrate which faces the pixel electrodes in an opposed manner as an inevitable component in a so-called vertical electric field system. Further, a reference signal line may be formed on the same substrate on which the pixel electrodes are formed and the holding capacitance is generated between the reference signal line and the pixel electrodes. Further, in a so-called lateral electric field system, the reference electrode is formed on the same substrate on which the pixel electrodes are mounted and the holding capacitance is generated between the pixel electrodes and the reference electrode or the reference signal line to which the reference electrode is connected.
By lowering the potential of the reference electrode below the level in the usual drive state such that the potential takes a value not more than a given negative value, the potential of the pixel electrodes is lowered due to the capacitive coupling. As a result, it becomes possible to realize the state in which the potential of the scanning signal lines is elevated to a voltage which enables the potential of the pixel electrodes to make the active elements assume the ON state. In this state, the charge stored in the pixel electrodes is rapidly released and the potential of the pixel electrodes rapidly approaches the potential of the reference electrode. Accordingly, it becomes possible to prevent the generation of flickering at the time of restarting the supplying of power.
Means 13.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the potential of the scanning signal lines is applied by a scanning signal line drive circuit and the scanning signal line drive circuit has a mode setting function which is capable of selecting either the state in which the scanning signal lines are sequentially selected or the state in which the scanning signal lines are simultaneously selected, the improvement is characterized in that the mode setting function has a state in which the scanning signal lines are set to a simultaneous selection after stopping the supplying of power to the liquid crystal display device from the outside.
Due to such a constitution, since all scanning signal lines assume the ON state after the interruption of the supplying of power to the liquid crystal display device, it becomes possible to rapidly release the charge from the pixel electrodes.
Means 14.
In a liquid crystal display device including first and second substrates which-are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the potential of the scanning signal lines is applied by a scanning signal line drive circuit, the position of the selected scanning signal line is determined in response to selection signal data inputted to the scanning signal line drive circuit, and the liquid crystal display device includes a control circuit which generates at least a clock which is inputted to the scanning signal drive circuit, the improvement is characterized in that the control circuit has a self-running mode in which the control circuits makes the clock continuously oscillated even in the state that signals are not inputted to the control circuit, and the selection signal data has the state in which the potential for instructing the selection after stopping the supplying of power to the liquid crystal display device from the outside is continuously held.
Various signals and clocks which are supplied to the video signal line drive circuit and the scanning signal line drive circuit in the inside of the liquid crystal display device are supplied through a control circuit (usually referred to as TCON: TFT Controller). The TCON is roughly classified into two kinds wherein one stops the output irrespective of the power supply when the input signals are stopped and the other which enters a self-running mode which generates existing signals or clocks when the input signals are stopped. Particularly, in the liquid crystal display device which adopts the TCOM having the latter self-running mode, even after the supplying of power is stopped, it is possible to make given clocks or signals oscillated until the potential of power for operation is lowered to a value equal to or below the operable potential. The length of time which enables such an oscillation can be set to a desired value of several ms to several seconds by providing a capacitor to the power supply which supplies power to the control circuit. Here, by holding the selection signal data at the selection potential, the number of scanning signal lines in the selection state can be increased for every clock so that the selection state of all lines can be realized eventually. Further, the clock in the self-running mode may elevate the frequency compared with the clocks in the usual operation mode and hence, all selected mode can be obtained in a further shorter time in this case. Accordingly, the charge stored in the pixel electrodes can be released so that the flickering can be suppressed.
Means 15.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements which are all mounted on one substrate, an orientation film which is inserted between the pixel electrodes and the liquid crystal layer and reference electrodes which are mounted on either one or the other substrate, wherein the potential of the scanning signal lines is applied by a scanning signal line drive circuit, the position of the selection scanning signal line is determined in response to selection signal data inputted to the scanning signal line drive circuit, and the liquid crystal display device includes a control circuit which generates at least a clock which is inputted to the scanning signal drive circuit, the improvement is characterized in that the control circuit has a self-running mode in which the control circuits makes the clock continuously oscillated even in the state that signals are not inputted to the control circuit, and the scanning signal line drive circuit is comprised of a plurality of groups of scanning signal line drive circuits and logic elements are provided between the groups of scanning signal line drive circuits, and the selection signal data are supplied in parallel to a plurality of groups of scanning signal line drive circuits by making the logic elements continuously assume the ON state after stopping the supplying of power to the liquid crystal display device from the outside.
Usually, the groups of the scanning signal line drive circuits, for example, gate driver ICs are connected in a cascade connection, wherein when the scanning performed by supplying the selection signal to the nth IC is finished, the selection signal is applied to the (n+1)th IC and the scanning signal line corresponding to the (n+1)th IC is sequentially selected. By constituting the logic circuits such that the logic circuit is provided to this signal interface part between the ICs and the selected signals are inputted to the respective ICs in parallel at the time of interrupting the supplying of power from the outside, the number of the scanning signal lines in the state that the respective ICs are simultaneously selected is increased for every inputting of clock and soon the full selection state is obtained. According to the constitution of this means, the time necessary for obtaining the full selection state using the means 4 can be reduced. For example, when the number of the gate driver ICs is three, the full selection state can be obtained within a time which is approximately ⅓ of the time necessary when the means 4 is used, and when the number of the gate driver ICs is six, the full selection state can be obtained within a time which is approximately ⅙ of the time necessary when the means 4 is used. Accordingly, the charge of the pixel electrodes can be rapidly released. At the same time, this implies that the operation continuation time of the TCON after the interruption of the supplying of power can be shortened. Accordingly, when a capacitor which supplies the potential for operating the TCON after the interruption of the supplying of power is provided, the capacitance can be reduced so that the low power consumption can be realized by an amount that the electric power stored in the capacitor is reduced.
Means 16.
In a liquid crystal display device including first and second substrates which are arranged to face each other in an opposed manner, a liquid crystal layer which is inserted between the first and second substrates, active elements, scanning signal lines for operating the active elements and pixel electrodes to which video signals are supplied upon operation of the active elements, video signal lines to which video signals are supplied and an orientation film which is inserted between the pixel electrodes and the liquid crystal layer which are all mounted on one substrate, and reference electrodes which are mounted on either one or the other substrate, wherein the potential of the scanning signal lines is applied by a scanning signal line drive circuit, the potential of the video signal lines is applied by a video signal drive circuit, and the polarity of the potential applied to the video signal lines from the video signal line drive circuit for the potential applied to the reference electrode is different between the neighboring video signal lines, the improvement is characterized in that the video signal line drive circuit has a function of changing over the state to a state in which the same potential is outputted to the neighboring video signal lines and the video signal line drive circuit has a state in which the function is performed after the interruption of the supplying of power to the liquid crystal display device from the outside so that the same given potential is applied to the neighboring video signal lines.
Here, by setting the given potential to the potential of the reference electrode, the subsequent storage of the charge to the pixel electrodes can be prevented. Further, by combining the above-mentioned provision with a technique which brings the scanning signal lines into the selection state, the release of the charge from the pixel electrodes can be surely realized.
By adopting at least one of the above-mentioned means, it becomes possible to suppress the holding of the charge in the pixel electrodes and hence, the liquid crystal display device which can solve the task of the present application and the image display device which can solve the task of the present application can be realized.
Further means and advantageous effects of the present invention will be apparent hereinafter in the following description including claims.